'Second-Skin' Sensor Could Track Your Health

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Imagine sticking a patch made of flexible electronics on your
skin that could read your body temperature, monitor your blood
circulation, even tell you when you need to put on sunscreen —
and that wouldn't leave the skin underneath it clammy the way
Band-Aids do.

A team of researchers at Northwestern University in Illinois and
the University of Illinois at Urbana–Champaign say they have
built such a patch, and it's about the size of a bandage. It's
made of plastic and thousands of tiny liquid crystals, not unlike
the ones that light up
computer and smartphone screens. It's so flexible that it
molds to the body like a second skin.

The device was made to detect changes in the temperature of the
skin beneath it; the liquid crystals change color in response to
body heat. There are so many crystals, some 3,600 of them, that
they can actually depict a heat map, or a picture of what lies
below the skin. "It's like the stuff they used to have in mood
rings," said John A. Rogers, a professor of materials science at
the University of Illinois whose lab collaborated on the project.
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This device, however, is sophisticated enough to diagnose very
real problems. The device reveals the temperature of the skin
beneath it with with high precision, which is important because
skin temperature reflects underlying characteristics, such as
blood flow, he said. And the device presents the data in a
useable format. "We can get a readout using color," Rogers told
Live Science.

A temperature-sensing device that could be
attached to a person's skin, and that is so unobtrusive that
people forget they are wearing it, would be a great help to
physicians, Rogers said.

For example, the device could reveal problems such as poor
circulation in the extremities, which can be a symptom of
diabetes, or an early sign of heart disease.

The device could also be used to detect some types of injuries in
the skin and tissue just underneath the sensor. This is because
the tissue near an injury site generally warms up, in a sign that
inflammation or infection might be on the way. The sensor could
also yield information such as how
hydrated the skin is, the researchers said.

To test their device, the researchers attached a small antenna
with the sensor, as well as a heating element. They sent a signal
to the antenna to turn on the heating element, and found they
could measure the distribution and diffusion of that heat through
the skin and tissue.

It's possible that researchers could add other kinds of sensors
to the device, too. For example, an ultraviolet light sensor
combined with a sensor for moisture could alert the wearer that
they are in danger
of getting sunburned, for instance if the UV levels are high
and the skin is becoming dry and hot.

And because the device allows air to pass through it, the skin
beneath the sensor can "breathe." That means users would not get
the clammy sweat that accumulates under bandages, which can cause
irritation, Rogers said.

The device is so small that it doesn't need a battery. There's a
wireless and flexible power system on the back, which can run on
power from a remote source, said Yihui Zhang, an assistant
professor of civil engineering at Northwestern and one of the
leaders of the research effort.

Rogers said the cost of the device should be relatively low,
since the sensor doesn't use any exotic materials or parts.
"We're talking about a few dollars," he said.

The scientists are working with a Cambridge, Massachusetts-based
company called MC10 Inc. to commercialize the technology.

A paper outlining the research appeared in the Sept. 19 issue of
the journal Nature Communications.